The Effects of Vertical vs. Horizontal plyometric Training on Sprinting Kinetics in Post Peak Height Female Student Athletes

Plyometric training is a form of jump training that is a useful method to improve sprinting speed due to its propensity to improve neural efficiency, increase joint stiffness and contraction speed. While research has shown that plyometrics can improve jumping and sprinting performance, no studies have compared the effects of different types of plyometric training on sprinting speed in young females. Therefore, the aim of the study was to compare different forms of plyometric training (horizontal and vertical) on sprinting performance in young females. Thirty young females from a private girls college were randomly divided into two groups and trained for seven weeks, twice a week; vertical plyometric (n=11, age 13.50 ± 0.96, peak heigh velocity-PHV: 1.60 ± 1.14), horizontal plyometric training (n=10, 13.40 ± 0.92, PHV:1.60 ± 0.93), and a physical education class as a control (n=15, age, 15.60 ± 0.31, PHV: 2.90 ± 0.55). Participants were tested for sprinting kinetics i.e. force (Fo), maximum power (Pmax), theoretical velocity (Vo), maximal velocity (Vmax), 10, 20 and 30 m split times using a radar gun over 30 m, isometric strength, vertical jump height and horizontal jump distance before and after the intervention. Both the intervention groups significantly improved all performance variables (g= 0.32- 1.30; p<0.05). The vertical group improved all kinetic variables except Fo and Pmax whereas the horizontal group improved all kinetic variables with a greater effect size g= 0.40-1.30. In comparison to the control group, the vertical group significantly improved Vo, Vmax, vertical and broad jump scores whereas the horizontal group significantly improved broad jump and 20 m split time scores (p<0.05). The findings of this study suggest that horizontal plyometric training is more effective in improving sprinting kinetics.

Deceleration Training in Team Sports: Another Potential ‘Vaccine’ for Sports-Related Injury?

High-intensity horizontal decelerations occur frequently in team sports and are typically performed to facilitate a reduction in momentum preceding a change of direction manoeuvre or following a sprinting action. The mechanical underpinnings of horizontal deceleration are unique compared to other high-intensity locomotive patterns (e.g., acceleration, maximal sprinting speed), and are characterised by a ground reaction force profile of high impact peaks and loading rates. The high mechanical loading conditions observed when performing rapid horizontal decelerations can lead to tissue damage and neuromuscular fatigue, which may diminish co-ordinative proficiency and an individual’s ability to skilfully dissipate braking loads. Furthermore, repetitive long-term deceleration loading cycles if not managed appropriately may propagate damage accumulation and offer an explanation for chronic aetiological consequences of the ‘mechanical fatigue failure’ phenomenon. Training strategies should look to enhance an athlete’s ability to skilfully dissipate braking loads, develop mechanically robust musculoskeletal structures, and ensure frequent high-intensity horizontal deceleration exposure in order to accustom individuals to the potentially damaging effects of intense decelerations that athletes will frequently perform in competition. Given the apparent importance of horizontal decelerations, in this Current Opinion article we provide considerations for sport science and medicine practitioners around the assessment, training and monitoring of horizontal deceleration. We feel these considerations could lead to new developments in injury-mitigation and physical development strategies in team sports.

Relationships between Fitness Status and Match Running Performance in Adult Women Soccer Players: A Cohort Study

Background and Objectives: The aim of this study was twofold: (i) to analyze the relationships between fitness status (repeated-sprint ability (RSA), aerobic performance, vertical height jump, and hip adductor and abductor strength) and match running performance in adult women soccer players and (ii) to explain variations in standardized total distance, HSR, and sprinting distances based on players’ fitness status. Materials and Methods: The study followed a cohort design. Twenty-two Portuguese women soccer players competing at the first-league level were monitored for 22 weeks. These players were tested three times during the cohort period. The measured parameters included isometric strength (hip adductor and abductor), vertical jump (squat and countermovement jump), linear sprint (10 and 30 m), change-of-direction (COD), repeated sprints (6 × 35 m), and intermittent endurance (Yo-Yo intermittent recovery test level 1). Data were also collected for several match running performance indicators (total distance covered and distance at different speed zones, accelerations/decelerations, maximum sprinting speed, and number of sprints) in 10 matches during the cohort. Results: Maximal linear sprint bouts presented large to very large correlations with explosive match-play actions (accelerations, decelerations, and sprint occurrences; r = −0.80 to −0.61). In addition, jump modalities and COD ability significantly predicted, respectively, in-game high-intensity accelerations (r = 0.69 to 0.75; R2 = 25%) and decelerations (r = −0.78 to −0.50; R2 = 23–24%). Furthermore, COD had significant explanatory power related to match running performance variance regardless of whether the testing and match performance outcomes were computed a few or several days apart. Conclusion: The present investigation can help conditioning professionals working with senior women soccer players to prescribe effective fitness tests to improve their forecasts of locomotor performance.

Anthropometric and physical performance of amateur rugby players within specific playing positions

BACKGROUND: This study examined the differences in physical and anthropometric traits between specific playing positions (i.e., forwards: front row, second row, back row; backs: half backs, centers, wings/fullbacks) in amateur rugby players and analyzed the magnitude of correlations among jump, sprint, and strength measures in forwards and backs. METHOD: Sixty-four male rugby players were assessed in anthropometrics, a variety of vertical jumps, 10- and 30-m sprint, and strength tests (i.e., squat and bench press). RESULTS: Front row forwards (FFR) demonstrated significantly higher body mass (BM) than second row (FSR) and back row (FBR) (107.4 ± 12.8, 99.1 ± 9.9 and 91.6 ± 7.6 kg respectively; p< 0.001). FFR showed greater absolute strength in bench press and squat, although no differences were found in relative strength. Regarding the differences in jump performance, FBR and FSR showed significantly (p< 0.05) and significant to non-significant (p= 0.042–0.078, ES = 0.90–1.55) higher jumps in all tasks compared to FFR. Moreover, FBR demonstrated lower sprint times and greater maximum sprinting speed (MSS) than FFR (p< 0.01). For the backs, centers (BCEN) were significantly heavier (p< 0.05) and exhibited a non-significantly moderate larger sprint momentum (p= 0.068, ES = 0.75) compared to half backs (BHB). MSS values were small to moderately greater in favor of wings/fullbacks [BWFB] (p= 0.188–0.059, ES = 0.50–0.71). Finally, statistically significant correlations were found between drop jump (flight time) and jump height across all jump tasks, sprint times and speed for both forwards (r= 0.541 to 0.996, p< 0.001) and backs (r= 0.422 to 0.995, p< 0.05). CONCLUSIONS: In conclusion, Front row forwards demonstrated significant, small to very large differences, when compared to their specific peers, whereas the backs were more similar. Additionally, our results indicated moderate to strong associations between explosive tasks such as sprinting and jumping in both playing positions.

Comparative Analysis of Soccer Performance Intensity of the Pre–Post-Lockdown COVID-19 in LaLiga™

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) forced a stoppage in the 2019/2020 season of LaLiga™, possibly influencing performance indicators in the return to competition. Therefore, here, we evaluated whether the stoppage due to the coronavirus 2019 disease (COVID-19) lockdown influenced physical performance compared to the start of LaLigaTM in terms of high-intensity efforts. Using a semi-automatic, multiple-camera system, running activities during 22 matches were analyzed. We compared the first 11 matches of the season (pre-lockdown) with the 11 matches just after the restart of LaLiga™ (post-lockdown). The results showed higher (p < 0.05) performance in the pre-lockdown period compared with the post-lockdown period, including in medium-speed running (14.1–21 km/h), high-speed running (21.1–24 km/h), and sprinting speed running distances (>24 km/h). However, the number of accelerations/min and decelerations/min were significantly higher during the post-lockdown period. Therefore, we conclude that the stoppage due to the COVID-19 lockdown generated lower physical performance in the post-lockdown period compared with the pre-lockdown period, most likely due to the accumulation of matches (congested schedules).

Kinematic Stride Characteristics of Maximal Sprint Running of Elite Sprinters – Verification of the “Swing-Pull Technique”

Maximum sprinting speed constitutes an optimum relation between the stride length and the step rate in addition to an appropriate sprinting technique. The kinematics of the sprint step at maximum sprinting speed have already been examined in numerous studies, without reaching a consensus. The aim of this study was to analyze the relationship between maximum sprinting speed and the stride kinematics based on the “Swing-Pull Technique”. German elite sprinters (N = 26, body height = 182 ± 6 cm, leg length 93.8 ± 4.1 cm) were tested while performing a 30-meter flying sprint at maximum sprinting speed. The relationship between sprinting speed and kinematic variables was determined via Pearson correlation. Sprinting speed (10.1 – 11.3 m/s) correlated with stride length (r = 0.53), ground contact time (r = -0.53) and variables from the technique model: the knee angle at the end of the knee lift swing (r = 0.40), the maximum knee angle prior to backswing (r = 0.40), the hip extension angle velocity (r = 0.63), and vertical foot velocity (r = 0.77) during pre-support, the ankle angle at the take-on (r = -0.43), knee flexion (r = -0.54), and knee extension (r = -0.47) during support. The results indicate that greater stride length, smaller contact time, and the mentioned kinematic step characteristics are relevant for the production of maximum sprinting speed in athletes at an intermediate to advanced performance level. The association of sprinting speed and these features should primarily be taken into account in conditioning and technical training.

Optimizing the load for peak power and peak velocity development during resisted sprinting

Introduction: Resistance towing is perhaps the most specific form of developing strength and power in muscles involved directly during the start, acceleration and at maximum speed. Resisted sprint training may involve towing a sled which provides an overload through the friction between the sled and ground surface or a modern advanced training device which uses drag technology to provide fully controlled resistance during the movement, such as the 1080 Sprint. The main objective of the study was to evaluate the optimal loading for the development of power in the engine assisted drag technology system SPRINT 1080. Material and methods: We evaluated the changes in running velocity and the generated force and power during resisted sprints over 30m with a load of 1, 3, 6, 9, 12 and 15 kg. Seven male sprinters with national and international experience participated in the study. Their average age, body mass and body height were 22.2 ± 2.4 years, 77.43 ± 4.63 kg, and 178.6 ± 3.2 cm, respectively. All athletes performed six 30 m sprints with 5 min rest intervals in between. The first sprint was performed without additional resistance, while the remaining 5 were performed in an random order with additional resistance of 3, 6, 9, 12 and 15 kg. After receiving a verbal signal, the participant started at will from a semi crouched position. During the resisted sprint trials, the time [s] and the following variables were recorded in peak values: power output [W], generated force [N], and sprinting velocity [m/s]. Results: Our results show that loading with 6 kg decreased sprinting velocity by 9.37% while the generated horizontal power increased by 31,32%. The 6 kg loading on the Sprint 1080device corresponded to 8% body mass, yet as mentioned before the baseline results were not fully free sprinting as the tested athletes reached velocities 0.5-0.6 m/s greater without the harness. Conclusion: Taking into account this fact, our results seem to confirm previous findings, that external loads between 8 and 13% may be optimal for improving power and sprinting speed at the same time.

shorts: An R Package for Modeling Short Sprints

Short sprint performance is one of the most distinguishable and admired physical trait in sports. Short sprints have been modeled using the mono-exponential equation that involves two parameters: (1) maximum sprinting speed (MSS) and (2) relative acceleration (TAU). The most common methods to assess short sprint performance are with a radar gun or timing gates. In this paper, we: 1) provide the {shorts} package that can model sprint timing data from these two sources; 2) discuss potential issues with assessing sprint time (synchronization and flying start, respectively); and 3) provide model definitions within the {shorts} package to help alleviate errors within the subsequent parameter outcomes.

Relationships between Linear Sprint, Lower-Body Power Output and Change of Direction Performance in Elite Soccer Players

The aim of this study was to investigate the relationship between linear sprint, power output obtained during a squat and change of direction (COD) performance. Fifteen elite soccer players participated in this study (age = 21.7 ± 0.72 years, body mass = 74.9 ± 9.11 kg, body height = 180.4 ± 7 cm, training experience = 9 ± 1.5 years). To examine these correlations a following battery of tests were carried out: 20-m linear sprint, one-repetition maximum (1RM) squat strength, peak power output obtained during a squat at 50% 1RM and time obtained in two 20-m COD tests with different angles of direction change (90° and 135°). In addition, COD deficits (90°-CODDEF and 135°-CODDEF) for both COD tests were calculated. The Spearman’s rank order correlation showed a nearly perfect statistical relationship between the 90°-COD and the 90°-CODDEF (r = 0.9; p < 0.001). In the case of 90°-CODDEF, there was a large statistical relationship with 135°-CODDEF (r = 0.59; p = 0.021). Moreover, there was a nearly perfect statistical relationship between 135°-COD and 135°-CODDEF (r = 0.91; p < 0.001). The statistically insignificant (p > 0.05) relationship between 20-m linear sprint time, power output obtained during a squat at 50% 1RM, 1RM squat strength level and both COD test, as well as both COD deficits were found. Results of the present study showed that 20-m linear sprinting speed, 1RM squat strength, power output obtained during squat at 50% 1RM and COD ability at 90° and 135° angles, are separate physical qualities. Moreover, it seems that COD deficit provides a more isolated measure of COD ability than the COD tests alone and does not must be limited to a specific angle, but provides knowledge about the COD ability in a range of other angles, at least concerning 90° and 135° COD angles.